The mammalian liver has a central role in short-term zinc homeostasis. This organ is composed of 2 principal cells groups, viz., parenchymal (PC; hepatocytes) and non-parenchymal (NPC) cells. The latter group contains both Kupffer (fixed macrophages) and endothelial cells. The relative functions that these various liver cells have in dietary and physiologically-induced alterations of general hepatic zinc content and metabolism are unknown. Likewise, the characteristics and regulatory aspects of Kupffer cell zinc transport and metabolism, as well as the effects of the zinc content of these cells on phagocytic capability, have not been investigated. These matters will be addressed in the proposed study. Liver cells will be isolated by the collagenase perfusion technique and purified by combining centrifugation and selective attachment procedures. In order to determine the cellular site(s) of hepatic zinc storage and cadmium detoxification, rats will be injected with the metallic salts 24 h prior to liver cell isolation. The metal content and the metallothionein (MT) levels of PC and NPC will be measured. PC and NPC will also be isolated from rats fed diets with various levels of zinc or stressed by either fasting, endotoxin administration or exposure to low temperatures. The zinc content and MT levels of these cells will also be determined. Primary cultures of Kupffer cells (KC) will be maintained as monolayers and the characteristics of zinc accumulation, efflux and subcellular distribution studied. The effects of various hormones on these parameters will also be tested. We will evaluate the effects of KC activation on zinc transport and metabolism, and conversely, the effect of the zinc content of KC on phagocytic ability. Finally, the specific mechanism(s) of zinc transport across the plasma membrane will be investigated in PC and KC using 65Zn, 125I-labelled albumin and transferrin for uptake studies.